The basic design and theory of function of archery bows remained unchanged for centuries until the relatively recent introduction of the compound bow. Such a bow includes over center, force multiplying pulley mechanisms effective to increase the energy stored by flexing bow limbs of a given resiliency and to reduce the draw poundage force necessary to maintain the bowstring in partially to fully drawn positions after a maximum draw poundage force at a partially drawn position is reached. It thus is recognized that the compound bow, as exemplified by the disclosure of U.S. Pat. No. 3,486,495, issued Dec. 30, 1969, represents a technological advance of immense proportions in this art. Since the introduction of the compound bow, this design has achieved dramatic commercial success, with the vast majority of archery bows manufactured and sold today being of the compound type.
This success is due in large part to the "let off" characteristics of compound bows enabling a bow of relatively high poundage to be held at full draw during aiming with a greatly reduced force while generating a larger arrow propelling force. Archers of given strength thus skillfully may use compound bows of greater poundage and the propensity for archer shaking at full draw during critical aiming, due to the archer being extended toward his maximum strength capabilities, greatly is reduced. In this respect, compound bow let off characteristics in the neighborhood of fifty percent are available.
The archery bow of this invention was designed to further increase let off characteristics over those of conventional compound bows, while sacrificing little potential energy stored during bow draw, and to provide certain other advantages over such conventional bows. In particular, the presence of compound bow bowstring extensions and/or auxiliary strings between the nocking point and handle, which may be contacted by arrow fletching between arrow release and free flight to cause deviation from the aimed arrow path, are eliminated. The resilient limbs are reverse loaded from those of conventional bows to flex away from the archer; a significant advantage in the event of failure of a limb. The individual limbs of the bow of this invention have their resilient deformation characteristics altered and tuned relative to one another by simple mechanical adjustments, thus eliminating a time consuming task required of a highly skilled workman during bow manufacture.
In addition, it is well known that in conventional compound bow, subsequent to arrow release and before free flight, the maximum propelling force on the arrow occurs at a bowstring position intermediate the at rest and full positions. In contradistinction, the bow of this invention provides what may be termed a "rocket effect" since the arrow propelling force increases from the full draw-release position to a maximum immediately preceding arrow free flight, similar to the manner in which a rocket powered vehicle is given maximum velocity by the expenditure of maximum rocket engine power immediately before free flight. It is believed that this effect will lead to greater accuracy and arrow velocity in bow operation.
It is, therefore, an object of this invention to provide a reverse load compound bow of greatly increased let off characteristics while sacrificing only a small part of the stored energy capabilities of the resilient limbs as compared to conventional compound bows. A further object of this invention is to provide a compound bow that eliminates a potential danger to the archer in the event of resilient limb failure. Yet another object of this invention is to provide a bow with the advantages described above, but that lends itself to more simple and less costly manufacturing methods than do commercial compound bows.